(i) Field of the Invention
The present invention relates to a sliding member which relatively slides against a counterpart member, particularly to a sliding member in which the friction coefficient of a sliding face varies along a relative sliding direction to the counterpart memeber.
(ii) Description of the Related Art
In a tall building, there is provided a damping device (hereinafter referred to as xe2x80x9cdamperxe2x80x9d) to prevent the building from being intensively vibrated by earthquake or the like. One type of damper utilizes the friction resistance of a sliding plate. This damper comprises sliding plates secured to braces which are fixed to a building structure and which cross each other in an X-shape, and a clamp mechanism by which these sliding plates are clamped in such a manner as they can slide to each other.
The clamp mechanism is constructed such that a motor is rotated clockwise or counter-clockwise in accordance with a building vibration degree to thereby change a clamping force (contact pressure) applied to the sliding plates, whereby the magnitude of a friction force occurring between the sliding plates is changed.
Here, the reason why the contact pressure of the sliding plates is changed in accordance with the building vibration degree is that, for example, when the building is slightly vibrated by wind, and the like, and if the contact pressure of the sliding plates is increased, the friction force of the sliding plates becomes excessively large, so that the slight vibration cannot be absorbed, and the vibration of the building is even enlarged. Conversely, when the building is intensively vibrated by earthquake or the like, and when the contact pressure of the sliding plates is small, the friction force is small, so that sufficient vibration damping effect cannot be obtained.
However, in the conventional damper constituted to change the contact pressure of the sliding plates and the friction force by use of the clamp mechanism using the motor as a drive source, when power stoppage accident occurs during earthquake, the control to raise the sliding plate contact pressure as described above cannot be performed. Another problem is that a backup power supply has to be installed for the power stoppage.
To solve the above-described problems, an object of the present invention is to provide a sliding member which can vary the friction force without varying the contact pressure.
In the sliding member of the present invention, since the friction coefficient of the sliding face varies along a sliding direction relative to a counterpart member, a friction force varies without changing a contact pressure with the counterpart member.
In this case, in order to allow the friction coefficient of the sliding face to vary along the sliding direction relative to the counterpart member, the kind of the sliding face material is selected to differ along the sliding direction of the counterpart member.
Moreover, by allowing the kind of the material forming the sliding face to differ in a plurality of parts, and by changing the area ratio of a plurality of parts formed of different kinds of materials along the sliding direction relative to the counterpart member, the friction coefficient of the sliding face may be constituted to vary along the sliding direction relative to the counterpart member.
The material of the sliding face may be selected from a metal, a synthetic resin, and a combination of the metal and the synthetic resin.